s1031.go (1857B)
1 package s1031 2 3 import ( 4 "go/types" 5 6 "honnef.co/go/tools/analysis/code" 7 "honnef.co/go/tools/analysis/facts/generated" 8 "honnef.co/go/tools/analysis/lint" 9 "honnef.co/go/tools/analysis/report" 10 "honnef.co/go/tools/go/types/typeutil" 11 "honnef.co/go/tools/pattern" 12 13 "golang.org/x/tools/go/analysis" 14 ) 15 16 var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{ 17 Analyzer: &analysis.Analyzer{ 18 Name: "S1031", 19 Run: run, 20 Requires: append([]*analysis.Analyzer{generated.Analyzer}, code.RequiredAnalyzers...), 21 }, 22 Doc: &lint.RawDocumentation{ 23 Title: `Omit redundant nil check around loop`, 24 Text: `You can use range on nil slices and maps, the loop will simply never 25 execute. This makes an additional nil check around the loop 26 unnecessary.`, 27 Before: ` 28 if s != nil { 29 for _, x := range s { 30 ... 31 } 32 }`, 33 After: ` 34 for _, x := range s { 35 ... 36 }`, 37 Since: "2017.1", 38 // MergeIfAll because x might be a channel under some build tags. 39 // you shouldn't write code like that… 40 MergeIf: lint.MergeIfAll, 41 }, 42 }) 43 44 var Analyzer = SCAnalyzer.Analyzer 45 46 var checkNilCheckAroundRangeQ = pattern.MustParse(` 47 (IfStmt 48 nil 49 (BinaryExpr x@(Object _) "!=" (Builtin "nil")) 50 [(RangeStmt _ _ _ x _)] 51 nil)`) 52 53 func run(pass *analysis.Pass) (any, error) { 54 for node, m := range code.Matches(pass, checkNilCheckAroundRangeQ) { 55 ok := typeutil.All(m.State["x"].(types.Object).Type(), func(term *types.Term) bool { 56 switch term.Type().Underlying().(type) { 57 case *types.Slice, *types.Map: 58 return true 59 case *types.TypeParam, *types.Chan, *types.Pointer, *types.Signature: 60 return false 61 default: 62 lint.ExhaustiveTypeSwitch(term.Type().Underlying()) 63 return false 64 } 65 }) 66 if ok { 67 report.Report(pass, node, "unnecessary nil check around range", report.ShortRange(), report.FilterGenerated()) 68 } 69 } 70 return nil, nil 71 }